Figure 3.

Adenoviral vector anatomy. The 36-kilobase double-stranded deoxyribonucleic acid (dsDNA) adenoviral genome is shown with open reading frames represented by block arrows. The E1A gene is the first gene synthesized and controls viral replication through a transcriptional cascade. E1A is replaced by fusions of foreign promoters and therapeutic genes in replication-attenuated vectors, or is re-inserted under the control of a foreign promoter in conditionally replicating vectors. E1B-55K can also be deleted to generate oncolytic vectors, previously thought to be reliant on p53 mutation. The E3 gene can be deleted to allow for larger transgene inserts. Three genes, E1B-55K, E4orf3, and E4orf6, participate in blocking dsDNA repair, leading to radiation sensitization. Two capsid encoding genes, fiber and penton, can be altered for transductional targeting.